A. The Polymer System
Within the last few decades, the art pertaining to polyurethane chemistry has seen a tremendous growth. As a result, polyurethane polymers of various kinds and forms are fairly well known. In general terms, the polyurethanes comprise polymers formed from a resin which has an active hydrogen atom and a polyisocyanate, such as a diisocyanate. Numerous resin systems now exist which have been combined in various ratios with the polyisocyanates, and the end polymers have ranged from rigid castable shapes to soft foams. Various polymer and prepolymer reactions for preparing the above types of polyurethanes have also been developed, and these reactions are fairly well explored.
Of the many resin systems which are known and the properties of which have been described, there are continuously being added new resin systems which in combination with the polyisocyanate overcome some vexing problems encountered with other resin systems or provide better properties for a particular end use. However, many of these resin systems a priori do not predicatably function in a given polymer system; and hence, the empirical observations still are at the foundation for the development of new resin systems as well as discovery of new polymers.
In addition, the various isocyanates which have been available (or proposed to be useful without being available) give different properties in any given resin system as well as give different properties from resin system to resin system. Hence, the predictability of end polymer properties cannot be inferred from a behavior of the resin system nor the behavior of this resin system in combination of isocyanate, except in very general terms. For this reason, the proper combination of the particular resin system with the proper isocyanate and the proper interaction or intercombination with each other is still an empirical art with the unpredictable end results.
Although many carrier and transport systems are known, the present polymer system is unique because the particular water absorbtivity, i.e., hydrophilicity may be tailored to suit the particular requirements of the system. Moreover, the same family but elastic and hydrophobic polyurethane polymer systems provide ready interfacial polymer media (medium) for applications where the polymer needs to be bound lightly to tenaciously to the substrate(s) and thus the delamination separation or incompatability phenomena encountered with prior art polymers are avoided.
Thus, a polymer system capable of diversely tailored properties is presented for use in a wide variety of applications. The prior art polymer systems have offered these properties in a narrow range with often inferior results for the use recited herein.
B. The Active Agent Systems
If the above novel polymer system is now used in combination with the active agent systems, many heretofore known systems are improved or supplanted because the combination of the polymer with the active agent offers novel carrier, membrane, release, coating, sensing, ion transport, i.e., dialysis or osmosis, etc. systems.
Representative active agent systems are:
1. pharmaceuticals;
2. bacteriostats;
3. viruscides;
4. insecticides;
5. herbicides;
6. larvicides;
7. fungicides;
8. algaecides;
9. nematocides;
10. topical or dermatological agents -- i.e., cosmetics, protective or screening, or moisturizing agents, etc.;
11. salts;
12. blocking agents;
13. pH regulators;
14. antifoulants for marine growth prevention;
15. screening agents, e.g., ultraviolet screening agents;
16. enzymes;
17. flavors, essences, or spices;
18. fragrances;
19. ion recognizers (reactants with);
20. humectants;
21. anti-oxidants;
22. absorbants; and
23. preservatives.
The above polymer and active agent system may be used as films or sheets in a single film or sheet combination or as multilayered film or sheet assemblage with or without a filler core and/or incorporating the above agents; as coatings either dip, tumble, or spray applied on a tablet or pill; as membranes, i.e., separating or barrier and incorporating the suitable agents from the list above; as liquid or creamy dispersions or hydrogels; as granules; as encapsulating films; as syrups; as powders, i.e., 100 mesh and smaller, i.e., to 10 micron size; as formed shapes of various configurations, e.g., rods, cubes, containing the active agent within the shape or in an interior space thereof; as inserts, i.e., body implants, pessaries, catheters; as tubes, conduits, channels, drains, screens, scrims, gauzes, etc., as conformable shapes, i.e., castable polymers with the active ingredient therein in single or multilayer.